| Summary: | 博士 === 國立臺灣海洋大學 === 材料工程研究所 === 101 === This study is aimed to evaluate the compressive strength, permeability and microstructure of cement-based composites containing fly ash and silica fume. The relationship between pore structure and corrosion behavior was investigated and compared.
Test results demonstrate that the addition of silica fume in cement-based composites was found to provide higher compressive strength, lower absorption, lower critical pore size, lower chloride diffusion coefficient and lower corrosion rate. The composites coataining 10% silica fumes provided better performance in permeability than those containing 5% silica fumes. This is because silica fumes can narrow down the size of large capillary pores and densify the pore structure. The addition of fly ash in composites also enhanced the compressive strength and permeability but is not as effective as silica fume. Unhydrated fly ash grains were observed in the porestructure and it caused the looser porestructure and reduced the permeability. The combination of fly ash and silica fume also enhanced the compressive strength and permeability and the specimens containing 5% silica fume and 10% fly ash had more increase in compressive strength and more decrease in permeability than those containing 5% silica fume or 15% fly ash and 25% fly ash. Moreover, corrosion rate, chloride diffusion coefficient and cricital pore size are suitable for evaluating the durability of cement-based composites. By regression analysis, there is high than 90% probability rebar corrosion when the corrosion rate is 11.54 μm/yr, or the chloride diffusion coefficient is 0.62x10-12 m2/s, or the cricital pore size is 26.71 nm.
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